1. Field of the Invention
The present invention relates to a magnetic field detecting element and a method for manufacturing the same. More particularly, the present invention relates to a magnetic field detecting element and a method for manufacturing the same by forming a soft magnetic core and a coil in a thin film type on a semiconductor substrate using a semiconductor process.
2. Description of the Related Art
Conventionally, a high sensitivity magnetic sensor has included a soft magnetic material and a coil. Such a magnetic sensor is generally manufactured by winding a coil on a soft magnetic core, and requires an electronic circuit for obtaining a magnetic field proportional to a measured magnetic field. Recently, a method for realizing a magnetic field detecting element of such a magnetic sensor has been suggested, in which a soft magnetic thin film core and a plane thin film coil are formed on a semiconductor substrate using a semiconductor process.
A general method for manufacturing a magnetic field detecting element using a semiconductor process is illustrated in FIGS. 1A through 1J.
Referring to FIG. 1A, a first seed film 2 is formed on a semiconductor substrate 1. A photoresist of a predetermined height (not shown) is formed on the first seed film 2. In FIG. 1B, a first plating mold 3 having a plurality of grooves 3a is formed by exposing and developing the photoresist. Next, the grooves 3a of the first plating mold 3 are filled with metal by a process, e.g., electric plating, so that a plurality of coil lines 4a, 4b, etc. are formed, as shown in FIG. 1C. Then, the first plating mold 3 and the seed film under the first plating mold 3 are removed, thereby forming a first coil 4 consisting of a plurality of coil lines 4a, 4b, etc., which are insulated from each other, as shown in FIG. 1D.
After the first coil 4 is formed, a first insulating film 5 is formed to cover the first coil 4 on the semiconductor substrate 1, as shown in FIG. 1E. Then, a soft magnetic material film (not shown) is formed on an upper surface of the first insulating film 5, and the soft magnetic material film is patterned and etched to form a soft magnetic core 6, as shown in FIG. 1F.
Subsequently, a second insulating film 7 of a predetermined thickness is formed on the soft magnetic core 6 of the semiconductor substrate 1, as shown in FIG. 1G. Then, as shown in FIG. 1H, via holes 8a and 8b for communicating with the coil lines 4a and 4o at either end of the first coil 4, are formed, and a second seed film 9 is formed to a predetermined thickness on an upper surface of the second insulating film 7. Next, a thick photoresist (not shown) is formed on the second seed film 9 and a second plating mold 10 having a plurality of grooves 10a and having the via holes 8a, 8b formed therethrough is formed by exposing and developing the thick photoresist.
As shown in FIG. 11, metal is formed in the plurality of grooves 10a of the second plating mold 10 so that a plurality of coil lines 11a, 11b, etc. is formed. Then, the second plating mold 10 and the second seed film 9 under the second plating mold 10 are removed, thereby forming a second coil 11 consisting of the plurality of coil lines 11a, 11b, etc., which are insulated each other, as shown in FIG. 1J.
Finally, although not shown, a protection film is spread on an upper portion of the second coil 11, whereby manufacturing of the magnetic field detecting element is complete.
However, according to the foregoing general method for manufacturing the magnetic field detecting element, the seed film 2 between the coil lines 4a, 4b, etc. should be removed so that the coil lines 4a, 4b, etc. constituting the first coil 4 are insulated from each other. For that purpose, after the first plating mold 3 is removed, the insulating film 5 must be formed on the first coil 4 for subsequent processes, thereby complicating the manufacturing process.
In addition, performance of the soft magnetic core 6 in the foregoing magnetic field detecting element is poor because the semiconductor substrate 1 for supporting the soft magnetic core 6 is uneven. Since the first coil 4 is projected onto the semiconductor substrate 1, the general magnetic field detecting element has a weakness in that the thickness of the first and the second insulating films 5, 7 may become thick. If the insulating films 5, 7 become thick, not only does the entire element become thick, but the process for forming the via holes 8a, 8b, which connect the first coil 4 with the second coil 11, becomes difficult. Also, a pitch between the coil lines, which influences performance of the sensor becomes large, causing further negative effects in the element.